Passive dosing dispensers of various geometries are disclosed in prior art patents. For instance, U.S. Pat. No. 650,161 which issued to J. Williams et al. on May 22, 1900 and U.S. Pat. No. 1,175,032 which issued to E. R. Williams on Mar. 14, 1916 disclose passive dispensers which are alternately flooded and then syphoned to a predetermined level. Also, U.S. Pat. No. 3,772,715 which issued to L. V. Nigro on Nov. 20, 1973, and U.S. Pat. No. 3,781,926 which issued to J. Levey on Jan. 1, 1974, and U.S. Pat. No. 3,943,582 which issued to J. Daeninckx et al. on Mar. 16, 1976 disclose passive dispensers which are alternately flooded and then gravitationally drained. Moreover, U.S. Pat. No. 3,407,412 which issued to C. T. Spear on Oct. 29, 1968, and U.S. Pat. No. 3,444,566 which issued to C. T. Spear on May 20, 1969 disclose dispensers which, although they have no moving parts, must be connected to a pressurized water supply such as the trap refill tube in a toilet tank and in which the direction of flow alternates in labyrinth passages. However, none of the aforementioned prior art patents disclose a passive dosing dispenser for the purpose described which has solved such problems as providing mixing of make-up water with product solution, and of providing product and product solution isolation from surrounding water during quiescent periods.
A significant advance over such prior art dispensers is disclosed in the co-pending patent application of Robert S. Dirksing, Ser. No. 897,477 filed Apr. 18, 1978 and entitled PASSIVE DOSING DISPENSER, said application being hereby incorporated herein by reference. A number of highly efficient passive dosing dispenser embodiments solving many of the problems inherent in such prior art dispensing apparatus are disclosed in the aforementioned patent application of Robert S. Dirksing. As is pointed out in said application with particular respect to dispenser embodiments of the type generally illustrated in FIGS. 1, 10, 11 and 12, the dispenser is initially made functional by filling the product solution reservoir in the dispenser with toilet tank water. This may be accomplished by immersing the dispenser several times in a body of water or by mounting the dispenser in a toilet tank and flushing the toilet several times. However, automatic dispensing of product solution from the reservoir will not take place until the reservoir has first been filled to a predetermined level. Thus, first flush dispensing of product solution with such dispensers cannot be assured without special care to fill the reservoir of the dispenser when the unit is first inserted into the toilet tank.
Failure to provide first flush dispensing of product solution is generally undesirable for two reasons. First, it may cause the consumer to believe the product to be dispensed is ineffective for its intended purpose, since there is no immediately perceptible result upon the first flush of the toilet after installation of the dispenser. Second, where two or more product solutions are to be simultaneously co-dispensed from dissimilar dispenser embodiments so as to produce a particular reaction with one another in cleansing and disinfecting the toilet bowl, it is highly desirable that co-dispensing of each product solution occur on each flush cycle to avoid confusion as to the desired form the reaction should take throughout the useful life of the co-dispensing unit.
Accordingly, it is an object of the present invention to provide a passive dosing dispenser of the type generally illustrated and described in connection with FIGS. 1, 10, 11 and 12 of the aforementioned patent application of Robert S. Dirksing, which dispenser will provide first flush dispensing of product solution without need for the consumer to exercise special care in filling the reservoir of the dispenser when initially inserting the unit into the toilet tank.